Reaction wood drying kinetics: tension wood in <Emphasis Type="Italic">Fagus sylvatica</Emphasis> and compression wood in <Emphasis Type="Italic">Picea abies</Emphasis>

The drying kinetics of reaction woods in Picea abies (compression wood) and Fagus sylvatica (tension wood) in comparison with their corresponding normal woods was investigated under constant convective drying conditions. Moisture profiles along the thickness of small flat-sawn boards taken from reaction and opposite wood zones were evaluated using a polychromatic X-ray system, a non-destructive method. The results revealed substantial differences in the drying behavior between the reaction and opposite woods. Both reaction woods represented slower drying rate than their matching normal woods mainly during the period of free water loss. However, the reaction and opposite woods reached the final moisture content (MC) of about 12% at the same time due to higher initial MC in the opposite woods. In the case of reaction wood, it took a longer time for the moisture profile to become approximately uniform. Overall, a more striking difference was observed in the drying behavior of compression and opposite wood in P. abies. Some important anatomical differences like the cell and pit dimensions and their proportion give some explanations for these drying behaviors.     

Effect of relative humidity on thermal degradation of Norway spruce (<Emphasis Type="Italic">Picea abies</Emphasis>) wood

The rate of thermal degradation of wood as a function of the extent of heat-bath treatment was investigated. At both 150°C and 170°C, the rate of degradation increased along with increasing relative humidity in the heating atmosphere. However, up to intermediate relative humidity (in the vicinity of 50%), the higher the temperature, the less was the effect of increasing relative humidity on the degradation rate. Furthermore, the greater the relative humidity, the less was the effect of increasing temperature on the degradation rate. On the other hand, between intermediate relative humidity and water-saturated conditions, the effect of increasing relative humidity on the degradation rate was the same regardless of the temperature, and the effect of increasing temperature on the degradation rate was the same regardless of the relative humidity. In moist conditions, significant thermal degradation occurred at temperatures as low as 150°C.     

Spatial pattern of beech (<Emphasis Type="Italic">Fagus sylvatica</Emphasis> L.) and oak (<Emphasis Type="Italic">Quercus pubescens</Emphasis> Mill.) seedlings in natural pine (<Emphasis Type="Italic">Pinus sylvestris</Emphasis> L.) woodlands

Spatial pattern of recruitment is an important factor influencing population dynamics of plant communities. The spatial pattern is determined by seed dispersal and by the spatial variability of germination and initial survival. In the process of forest expansion following farmland abandonment, mid- and late-successional species are often dispersed in pioneer forests by birds. This could result in an aggregated spatial pattern of seeds that could influence the dynamics of these species in mixed pioneer forests. In the sub-Mediterranean area, mid- and late-successional species such as Quercus pubescens (downy oak) and Fagus sylvatica (European beech) are expected to replace pioneer Pinus species. Using a point sampling method we demonstrated that beech and oak seedlings (height <2 m) have a clumped distribution in the understorey of pine. This could result from an aggregated dispersal by jays (dispersal effect) or from preferential recruitment in particular habitats (habitat effect). To test these hypotheses we proposed a statistical analysis of spatial patterns of regeneration of beech and oak. Ground cover variables (i.e. cover by rock outcrops, herbs, box shrubs, mosses or pine) did not differ significantly around seedlings as compared with random sample plots. Likewise, clumped seedlings had growth similar to isolated seedlings, thus refuting the hypothesis of preferential location in the most favourable microsites. Aggregated dispersal seems to be involved in the process of regeneration. Since beech and oak seedlings have contrasting ecological demands, we discuss the implication of this pattern for the replacement dynamics of pine by these species.     

Crystallinity of wood and the size of cellulose crystallites in Norway spruce (<Emphasis Type="Italic">Picea abies</Emphasis>)

X-ray diffraction was used to study variations in the crystallinity of wood and the average thickness and length of the crystallites of cellulose as a function of the number of the year ring in Norway spruce [Picea abies (L.) Karst.]. The crystallinity increased from ring 4 to ring 10 from the pith and was constant after ring 10. The crystallinity of mature wood was about 30% ± 5%. The average thickness and average length of the crystallites were 3.2 ± 0.1nm and 28 ± 2nm, respectively; and no systematic variation of these values with the number of the year ring was observed. The mean microfibril angle decreased near the pith but was constant in the mature wood.     

Biomass expansion factors for Sitka spruce (<Emphasis Type="Italic">Picea sitchensis</Emphasis> (Bong.) Carr.) in Ireland

The assessment of a forest resource in national inventories provides a firm basis for the calculation of biomass and carbon (C) stocks of forests. Biomass expansion factors (BEFs) and conversion factors provide a robust and simple method of converting from forest tree stem volume to total forest biomass. These factors should be constructed on the basis of nationally specific data in order to take account of regional differences in growth rates, management practices, etc. The objective of this study is to improve the accuracy of biomass estimation by calculating a range of age-dependant BEFs from representative data that more accurately describe the allometry of present forests. The results from this study show that the allocation of biomass to compartments in forest stands and throughout a rotation varies considerably, and that the use of BEFs for the calculation of C stocks in forests of sub-timber dimensions is highly impractical.

The onset of hazel wood formation in Norway spruce (<Emphasis Type="Italic">Picea abies</Emphasis> [L.] Karst.) stems

Key message

Fungal infection was outlined as a potential reason for the onset of indented annual growth ring formation during the juvenile phase of hazel wood growth. Annual growth ring indentations resulted from the formation of disturbed zones which originated solely in close proximity to leaf traces.

Context

Hazel wood is an abnormal type of woody tissue that is formed as a result of exogenous stimuli that may trigger long-term responses in the cambium. Cambial responses produce anatomical alterations in the surrounding xylem tissue that can be observed as an indentation of annual growth rings. The chemical profiles of lignan hydroxymatairesinol may provide an indication of its possible role in the protection of a living tree against the spread of a fungal or microbial infection at the onset of indentation.

Aims

The objectives of this study were to reveal the anatomical differences in the altered woody tissue of Picea abies hazel wood at both the onset and the later stages of annual growth ring indentation and to determine the chemical profiles for hydroxymatairesinol upon elicitation by a fungal infection in the disturbed zones.

Methods

Light and scanning electron microscopy observations were carried out on radial, tangential, and cross sections of hazel wood zones separated from P. abies stems. Concentrations of hydroxymatairesinol were determined for both the disturbed zones and the non-indented zones using a gradient high-performance liquid chromatography.

Results

The formation of disturbed zones was accompanied by significant changes in both the direction and width of the tracheids which produced an abnormal formation of intertwined and twisted tracheids. Fungal hyphae, radial cell wall cracks, and unusually large cross-field pitting were all found in the tracheids of the disturbed zones.

Conclusion

The content of hydroxymatairesinol in the acetone extract determined from the disturbed zones was 3.4 times greater than that present in the non-disturbed tissues. By means of vascular dysfunction in the leaf traces, host trees responded to the fungal infection by plugging the lumens of conductive leaf trace tissue and filling the vascular pathway with polyphenolic compound deposits.

     

Fracture in Norway spruce wood treated with <Emphasis Type="Italic">Physisporinus vitreus</Emphasis>

Changes in the fracture behaviour of Norway spruce tonewood after fungal treatment were studied. Specimens were incubated for 6, 9 and 12 months with Physisporinus (P.) vitreus. Fracture tests were performed in a compact-tension fracture experiment set-up, and the results were compared with the morphological analysis of the degraded wood structure and transverse sections of the crack tip viewed under light and fluorescence microscopy. It was evident that both the failure load and critical stress intensity factors were reduced in wood after prolonged incubation periods. Weight losses were significantly higher in sapwood than in heartwood. With prolonged incubation periods, the frequency of unstable fracture and brittle behaviour of the wood increased. In untreated wood, cracks were initiated in the earlywood. The process involved both delamination of the cells within the middle lamellae and rupture of the cell walls, inducing a zigzag crack tip pattern. In fungally treated wood, cracks often commenced from the intersection between late- and earlywood, resulting in a straight tangential crack line. Micrographic images showed that P. vitreus was more active in the secondary walls of latewood tracheids. In this region of the wood, the cell walls were strongly degraded after 9–12 months of incubation, resulting in a reduction in tensile strength, even though the wood did not show strong features of decay at the macroscopic level.     

Rapid assessment of wood traits for large-scale breeding selection in <Emphasis Type="Italic">Picea mariana</Emphasis> [Mill.] B.S.P.

Key message

Pilodyn and acoustic velocity measurements on standing trees, used for predicting density and stiffness, can be good genetic selection tools for black spruce. Genetic parameters and selection efficiency were conserved in two breeding zones with contrasted bioclimatic conditions.

Context

Given the recent progress made in the black spruce genetic improvement program, the integration of juvenile wood mechanical properties as selection criteria is increasingly relevant.

Aims

This study aims to estimate the genetic parameters of in situ wood density and modulus of elasticity (MoE) measurements and to verify the efficiency of various measuring methods used for large-scale selection of black spruce based on wood quality.

Methods

Height, diameter, wood density, and some indirect measures of density (penetration and drilling resistance) and MoE (acoustical velocity and Pilodyn) were estimated on 2400 24-year-old trees of 120 open-pollinated families in progeny trials located in the continuous boreal or mixed forest subzones.

Results

Heritability of growth, density, and indirect density measurements varied from low to moderate and was moderate for acoustical velocity in both vegetation subzones. Expected genetic gains for wood properties based on in situ methods were higher for MoE proxy estimation combining Pilodyn and acoustic velocity.

Conclusion

Acoustic velocity is a good predictor of MoE. It is virtually unaffected by the environment and can be used on a large scale in the same manner as the Pilodyn for density. Using a proxy estimation that combines both methods helps optimize genetic gain for MoE.

     

Quality of growth substrates of post-disturbed lowland black spruce sites for black spruce (<Emphasis Type="Italic">Picea mariana</Emphasis>) seedling growth

Black spruce (Picea mariana (Mill.) BSP) is the most important commercial tree species in the eastern boreal forest of Canada. Only limited work has been conducted to assess the quality of the various substrates that are found on post-disturbed sites prone to paludification having an effect on black spruce seedling growth. The objectives of this study were (1) to use a pot test to assess black spruce seedling performance on substrates found at the soil surface, in the rooting zone of undisturbed soil, at depths that become available to spruce roots after soil disturbance by wildfire or through management; and (2) to determine the nutritional quality of these substrates when constraints of poor drainage are artificially removed. Black spruce growth was greatest with fibric Pleurozium in the rooting zone, and with burned fibric Pleurozium and living Sphagnum at the soil surface. Good seedling growth on different substrates found in the rooting zone was associated with higher N and P foliar concentrations. Based on these results, we recommend targeted planting of black spruce seedlings in substrates of Pleurozium origin and the development of management techniques that promote Pleurozium schreberi. The Canadian Crown’s right to retain a non-exclusive royalty-free licence in and to any copyright is acknowledged.     

Adaptation to common optimum in different populations of Norway spruce (<Emphasis Type="Italic">Picea abies</Emphasis> Karst.)

Responses of Norway spruce populations to climatic transfer, in terms of growth and survival, were analyzed on the basis of a provenance experiment derived from the international provenance test IUFRO 1964/1968. The experiment comprises a series of five trial plots situated at contrasting elevations ranging from 484 to 1,275 m a.s.l., with 11 provenances represented at all trial plots that were used for the analysis. Transfer rates were defined as differences in altitudes or climatic variables between the site of plantation and the site of origin. Optimal transfer rates and optimal climates for individual provenances were derived from quadratic response functions. Spruce provenances generally responded positively by height and volume growth to transfer into lower altitudes, i.e., warmer conditions with less precipitations. The analysis at the level of provenances showed that optimal transfer rates were consistently negatively correlated with the underlying environmental variables and optimal climates were consequently nearly the same for all provenances irrespective of the response traits and ecodistance variables. Stability indices based on joint regression analysis indicate that provenances from higher altitudes, colder and wetter climates tend to be more stable, whereas provenances from lower altitudes, drier and warmer sites are more responsive to site quality. However, the differences in the stability are small and stability indices were generally close to 1. The results indicate that populations in different climates remain adapted to a common optimum and the extent of local adaptation is quite limited. Possible explanations of this observation are briefly discussed.     

Stand density and growth of Norway spruce (<Emphasis Type="Italic">Picea abies</Emphasis> (L.) Karst.) and European beech (<Emphasis Type="Italic">Fagus sylvatica</Emphasis> L.): evidence from long-term experimental plots

On the basis of nine Norway spruce (Picea abies (L.) Karst.) and ten European beech (Fagus sylvatica L.) thinning experiments in Germany, for which both residual and removed stock had been registered first during 1870, I scrutinize how moderate and heavy thinning from below (B-, C-grade) affects the production of merchantable volume compared with light thinning (A-grade). In relation to A-grade, cumulative merchantable volume (CV) of B- and C-grade amounts in average to 103–107% in juvenile and to 97–102% in mature Norway spruce stands. The corresponding findings for European beech are 101–106% and 94–102%. CV of individual stands varies between 89% and 130% for Norway spruce and 73% and 155% for European beech (CV of A-grade = 100%). These findings are substantiated by the relation between stand density (SDI) and periodic annual increment (PAI). On the B- and C-grade plots of spruce and beech, respectively, SDI was reduced down to 41–91% and 31–83% of the A-grade. When SDI is reduced in young stands, PAI follows a unimodal curve. Norway spruce’s PAI culminates in 109% if SDI is reduced to 59%; European beech’s PAI culminates in 123% when density is reduced to 50%. Whereas Norway spruce’s growth reacts most positively on thinning under poor site conditions and with increment reduction on favourable sites, European beech behaves oppositely. With stand development the culmination point of the unimodal relation moves towards maximum density, so that in older stands PAI follows the increasing pattern, which is the left portion of a unimodal curve. A model is presented which apparently unifies contradictory patterns of stand density–growth reactions by integrating relative stand density, average tree size and site fertility effects, and makes the findings operable for forest management.     

Bioremediation of CCA-treated wood by brown-rot fungi <Emphasis Type="Italic">Fomitopsis palustris</Emphasis>, <Emphasis Type="Italic">Coniophora puteana</Emphasis>, and <Emphasis Type="Italic">Laetiporus sulphureus</Emphasis>

This study evaluated oxalic acid accumulation and bioremediation of chromated copper arsenate (CCA)-treated wood by three brown-rot fungi Fomitopsis palustris, Coniophora puteana, and Laetiporus sulphureus. The fungi were first cultivated in a fermentation broth to accumulate oxalic acid. Bioremediation of CCA-treated wood was then carried out by leaching of heavy metals with oxalic acid over a 10-day fermentation period. Higher amounts of oxalic acid were produced by F. palustris and L. sulphureus compared with C. puteana. After 10-day fermentation, oxalic acid accumulation reached 4.2 g/l and 3.2 g/l for these fungi, respectively. Fomitopsis palustris and L. sulphureus exposed to CCA-treated sawdust for 10 days showed a decrease in arsenic of 100% and 85%, respectively; however, C. puteana remediation removed only 18% arsenic from CCA-treated sawdust. Likewise, chromium removal in F. palustris and L. sulphureus remediation processes was higher than those for C. puteana. This was attributed to low oxalic acid accumulation. These results suggest that F. palustris and L. sulphureus remediation processes can remove inorganic metal compounds via oxalic acid production by increasing the acidity of the substrate and increasing the solubility of the metals.An erratum to this article can be found at     

Modelling the risks of natural stand closure release with ageing in pure beech (<Emphasis Type="Italic">Fagus sylvatica</Emphasis>) and spruce (<Emphasis Type="Italic">Picea abies</Emphasis>) stands

• Background  

In the development of pure beech and pure spruce pristine forests, we assume there should be a continuous transition from full stocking to successive disintegration and, finally, total replacement of the first generational wave at the end of its lifetime, dependent on mortality due to overcrowding as well as ageing, leading newly recruited cohorts to grow up from below.     

Fertility variation in endemic populations of Ehrami black pine (<Emphasis Type="Italic">Pinus nigra</Emphasis> Arnold. subsp. <Emphasis Type="Italic">pallasiana</Emphasis> var. <Emphasis Type="Italic">pyramidata</Emphasis>)

Fertility variation and effective number of parents were estimated in the 100 individuals from each of three plantation populations (P1, P2 and P3) of the endangered Pinus nigra. subsp. pallasiana var. pyramidata established in the Isparta–Golcuk district in southern Turkey in 1990. Potential relations between cone yield and growth characters (height, diameter at breast height, diameter at base and crown diameter) were also investigated. Large differences were found among populations and within populations for cone production and growth characters. Mean cone production was eight (ranging from 6.5 in P2 to 9.1 in P1) for the three populations. The 10 most productive individuals for cones produced 32% of the total cones in P1, 39% in P2 and 34% in P3; 21, 16 and 6 individuals, respectively did not produce any cones in the populations. According to the correlation analyses, the relation between cone yield and growth characters changed for the populations, while height, diameter at breast height and crown diameter were positively significantly correlated (r = 0.182, 0.135 and 0.209; p ≤ 0.05) with cone production for the three populations. Fertility variation was 1.81 in total of three populations, ranging from 1.72 in P3 to 3.45 in P1). Effective number of parents was 142 (55.2 of number of parents censused; 29%, P1; 49.8%, P2; 58.3%, P3).     

Pathogenic effects of <Emphasis Type="Italic">Xenorhabdus nematophilus</Emphasis> and <Emphasis Type="Italic">Photorhabdus luminescens</Emphasis> (Enterobacteriaceae) against pupae of the Diamondback Moth, <Emphasis Type="Italic">Plutella xylostella</Emphasis> (L.)

The relationship between Xenorhabdus nematophilus and Photorhabdus luminescens, the bacterial symbionts of the entomopathogenic nematodes Steinernema carpocapsae and Heterorhabditis bacteriophora, against the diamondback moth, P. xylostella (L.), pupae showed the pathogenic capability of P. luminescens to be over that of X. nematophilus. They gave 60 and 40?% mortality with LC₅₀ values of 5?×?10⁴ and 5.5?×?10⁵ cells/ml, respectively.The number of bacterial cells influences the rate of killing the pupae of P. xylostella and a direct correlation between mortality of the pupae, percentage of deformed adults and the spraying dose with significant differences were observed. An inverse correlation found between the no. of eggs laid/female, percentage of hatching, adult survival and the spraying dose. These bacterial effects have been attributed to different toxic bacterial enzymes which damage the haemocytes and inhibit activation of the humoral immune system of the insect.     

Enzymatic saccharification and ethanol production of <Emphasis Type="Italic">Acacia mangium</Emphasis> and <Emphasis Type="Italic">Paraserianthes falcataria</Emphasis> wood,and <Emphasis Type="Italic">Elaeis guineensis</Emphasis> trunk

We examined the saccharification and fermentation of meals from Acacia mangium wood, Paraserianthes falcataria wood, and Elaeis guineensis trunk. The levels of enzymatic hydrolysis of cellulose and ethanol production were highest for P. falcataria wood and lowest for A. mangium wood. Ultrasonication pretreatment of meal further increased the rates of hydrolysis and ethanol production in meal from P. falcataria wood. Through this pretreatment, hemicelluloses (xylan and xyloglucan) and cellulose were released in the meal from P. falcataria wood. Loosening of hemicellulose associations can be expected to make P. falcataria wood more useful for bioethanol production.     

<Emphasis Type="Italic">Bursaphelenchus mucronatus</Emphasis> (Nematoda: Aphelenchoididae) vectored by <Emphasis Type="Italic">Monochamus </Emphasis><Emphasis Type="Italic">urussovi</Emphasis> (Coleoptera: Cerambycidae) in Hokkaido,Japan

Bursaphelenchus mucronatus Mamiya et Enda has been recovered for the first time from adults of the cerambycid beetle, Monochamus urussovi (Fischer), in Hokkaido, Japan. The nematode was also recovered from the inner bark of Picea jezoensis (Siebold et Zuccarini) Carrière and Abies sachalinensis (Fr Schmidt) Masters infested with M. urussovi larvae. PCR–RFLP analysis indicated that B. mucronatus in Hokkaido is the European type.     

Physical properties of thinning wood in maritime pine (<Emphasis Type="Italic">Pinus pinaster</Emphasis> Ait.): case study

Forty young trees from a stand of maritime pine in the southern mountains of Galicia, Spain (42°21′N: 8°01′W) were felled to obtain the material required for studying density and shrinkage in clear and small wood specimens. The wood ranged from light to moderately heavy, and the dimensions remained reasonably stable with varying moisture content. The results were consistent with those obtained in previous studies of adult trees, except for axial shrinkage, which was very high and variable in this study. The between-tree variation in wood properties was high considering that the sampled trees came from the same stand. However, the relationships between density and height in the stem were similar in all trees. A general model for the prediction of volumetric shrinkage was developed, with oven-dry density and ring width as predictor variables. The model is feasible for estimation of wood quality in living trees. It is applicable to tree selection for thinning and for genetic improvement of stock.     

Successful <Emphasis Type="Italic">Agrobacterium</Emphasis>-mediated transformation of <Emphasis Type="Italic">Populus tomentosa</Emphasis> with apple <Emphasis Type="Italic">SPDS</Emphasis> gene

The problem of salinized soils has become one of the most serious constraints to agricultural and forest productivity. With the purpose of enhancing salt stress tolerance of Populus tomentosa, we transformed this tree species with spermidine synthase （SPDS） genes derived from an apple by an Agrobacterium-mediated method. Four transgenic clones were confu＇med by PCR and Southern blot analysis. As well, the expression of introduced SPDS genes was analyzed by real-time quantitative PCR.     

Effectiveness of Neem (<Emphasis Type="Italic">Azadirachta indica</Emphasis>) insecticides against Brassica pod midge (<Emphasis Type="Italic">Dasineura brassicae</Emphasis> Winn<Emphasis Type="Italic">.</Emphasis>)

The efficiency of the botanical insecticide (BI) NeemAzal T/S (containing 1% Azadirachtin A), on the basis of azadirachtin applied in a dose of 20 g a.i. ha⁻¹ against Brassica pod midge (Dasineura brassicae), has been monitored for 4 years. The biological efficiency of BI was compared with the efficiency of some synthetic insecticides. It was ascertained that BI was very efficient in decreasing the number of damaged oilseed rape pods (ranging from 56.5 to 85.9% compared to untreated plants) and its efficiency was comparable with synthetic insecticides based on Chloronicotinyl (Thiacloprid) and Neonicotinoid (Acetamiprid). BI’s efficiency was, in some years, even significantly higher compared to pyrethroid (λ-cyhalothrin). The high biological efficiency of azadirachtin that we ascertained was significantly reflected in increasing potential crop yields. The yield increase of azadirachtin ranged between 9.3 and 19.4% compared to the control sample. Azadirachtin showed the highest yield for the whole time of experimentation, and in some years the yield increase was significantly higher compared to some synthetic agents.